I was recently involved in a discussion about walk-on characters, those characters that only appear for a few lines or less. They're usually assumed to be important to the story, but they don't play so big a role that they are fleshed out with the detail of a main character.
The discussion raised the question of how much reality such a characterneeds. To what lengths should we go to avoid "cardboard" characters (i.e., characters that are flat, two-dimensional, or stereotypical.)
The real world, when seen through the eyes of a character, can often have some cardboard in it. If a writer is giving us the world through the eyes and mind of a character, then the writer should stay true to that perspective when it comes to walk-on characters.
Let's say my main character gets pulled over on the way to the airport. The cop, of course, is a real character. He has forty-two years of detailed back-story, all of which is influenced by other characters, each with equally complex and layered stories.
But my main character is trying to get to the airport. How will she make it before Jorge's plane takes off? How can she convince this idiot of her urgency? Should she tell him everything? No--maybe just make a run for it. She could shout out a warning about the bomb before this pig tackles her and slaps on the handcuffs.
She doesn't have time to learn about the cop's interest in My Little Pony, or his opinions on how the Korean War veterans were treated, or his thoughts on why Led Zeppelin really broke up. She's too preoccupied with the crisis at hand to notice that his uniform is wrinkled and mustard-stained.
So, in her eyes, he is starting out as a cardboard character. But since I only have twelve lines, that may not be bad. I think the trick with some walk-on characters is to allow a little cardboard, just not 100%.
So I have a lazy country-road cop walking up to her car. What's the usual line? "License and registration please?" To give this guy a little color and break away from the cardboard mold a little, I make him stand out in a way my MC can't help but notice.
"Well, little miss, what say we skip the license and registration bullshit and you just give me your phone number instead?"
Now that she's noticed him, I can go back to those details and add some more flavor. These actually reinforce the stereotype I began with. She sees the mustard stain and crinkled clothes because she has a reason to notice. I could also throw some variety in there to offset the cardboard--maybe one of those little pink breast-cancer ribbons, except maybe his is a little different.
Then, after a little arguing and resisting his advances--making it clear she will call his superior and press charges for harassment--he can refer to her as one of those "Damn hippies." Or say that she "probably voted for Obama."
I could do more, but do I need to?
The cardboard became a tool, not a thing to fear. It's not a polished example, but I tried to use the cardboard as a springboard into something more memorable. It also puts the character in a situation where she has to make some choices, which then reveals her character a little more.
Now, given more time I could do away with the cardboard and use more complex detail. But I think that given only a few lines, it's a valid way to make a character vivid without trying to force unnecessary details into the scene--details the character would never notice or care about, in many cases.
Writer of speculative fiction. Current work in progress is an untitled dark fantasy novella.